Laws don't stop that.
Criminals get better firearms than I can lawfully buy.
Your premise is flawed.
If you have a permit, your complying. It is only a matter of time before the love of freedom and concern for the 2nd amendment is bred out of the country.
So, no the Feds wont, nor will they need to show up at the door to ask for the gun.
If a law banning firearms were to be passed and signed by obama, probably half the gun owners, if not more, wouldn’t know about it unless it was announced on AMERICAN IDOL.